High speed motion picture cameras are well known in the art and most operate on the principle of providing a continuous film movement so that high film speed can be achieved as opposed to the usual intermittent film movement. To provide the desired succession of images on the film, a multi-surfaced rotating prism is employed to move the imaged scene in the film gate at the same speed as movement of the film, a shutter interrupting this operation after completion of rotation of the multi-surfaced prism through a given circumferential distance and the start of an image formation by the next surface of the prism.
A typical example of the foregoing type of high speed movie camera is shown and described in U.S. Pat. No. 3,259,448 issued July 5, 1966 which represents the closest prior art of which Applicant is aware.
The foregoing patent describes a high speed movie camera incorporating various improvements over previous high speed movie cameras principally resulting in a more compact configuration than theretofore available and better registration and synchronization by positively interconnecting the shutter with the rotating multi-faced prism and a sprocket roller controlling movement of the film through the film gate imaging plane. Part of the increased compactness has also been realized by folding the optical path of light from the objective lens to the imaging plane at the film gate.
Cameras of the foregoing type are capable of photographing scenes at the rate of 10,000 frames per second. At such high speeds, one of the major problems introduced is a tendency for movement or jiggling of the position of the transversely extending vertical frame lines on the film. This disadvantage is a result of non-uniform tension in the portion of the film passing through the film gate where the scene is imaged onto the moving film. Another problem with such cameras is that in providing the folded optical path a relatively large number of light directing optical surfaces are required either in the form of mirrors or right angled prisms.
Further improvements in high speed motion picture cameras are thus needed to correct the foregoing deficiencies.